The bottleneck in structure determination by X-ray crystallography is crystallization, where roughly 70% of purified proteins fail. Two major reasons proteins fail to enter the crystalline state are having too few lattice contacts, and having multipe conformations, often the result of missing partner proteins. The purpose of this project is to overcome barriers to crystallization. The key overall ideas in this project are that crystallizatio of a macromolecule or complex can be improved by (1) presenting this macromolecule in a form that is highly suitable for crystallization and (2) creating many different forms of the macromolecule. These themes of optimizing crystallizability and variation are central to all three components of this projects. The innovation new methods we propose to develop will use a combination of natural binding partners and binding modules to improve crystallization of a target macromolecule by (1) creating many different forms of a molecule to crystallize and (2) finding a natural partner macromolecule that stabilizes and enhances the crystallizability of a target macromolecule. Many forms of a molecule will be created using a panel of symmetry-forming modules that can be linked to the target molecule. These modules will be antibody- or green fluorescent protein-based. Natural binding partners will be found with a combination of novel bioinformatics and experimental approaches. The transformative methods are scalable, synergistic, and offer the potential of accelerating results in both structural biology and structual genomics by providing a molecular toolkit for diversifying the potential crystallization arrangements and symmetries of targeted proteins. This program project will be carried out by our UCLA/ Los Alamos team as three tightly integrated subprojects, each involving researchers from both UCLA and Los Alamos. This work will lead to methods that will be used by the structural biology community to determine structures of proteins that will increase our understanding of human health and our ability to cure human disease.